Known in the art are horizontal cutting machines whose purpose is to provide two new single bottles by separating the two bodies of a double-bodied bottle manufactured previously by means of blowing, extrusion or other shaping methods.
On such machines the bottles reach a cutting station in horizontal position by means of a conveyor belt with dividing segments and an end ramp. As the cut is made the bottles move along resting on a pair of tracks. A drive belt situated above the tracks makes contact with the upper part of the bottle, making it advance and rotate about its own axis. As the bottle advances a fixed blade located between the two tracks and gradually increasing their height performs the cut. Thanks to the bottle shifting and rotation movement the cut is made around the entire perimeter of the neck. When the cut is completed, the two bottles and the central attaching part are ejected.
These machines have the disadvantage that the rotation of the bottles becomes imprecise as their passing speed increases, since the rotation resistance caused by the cutting action of the blade disturbs the bottle's travel-path, in which the bottle has only one point of contact with the support tracks and another with the drive belt. Furthermore, in order to implement the cutting of the bottles there has to be a certain space between them, since the bottle has to be able to rotate freely as the cut is being made, with no means other than the tracks and the drive belt in contact with it. All these factors have an adverse effect on productivity, as the bottles often fall over or their path deviates at the cut is made. Moreover, the limited cutting speed and the space that has to be left between one bottle and the next also reduces the output of the system.
This system further requires the cut to be made in a straight line, so that the machine takes up a considerable amount of space.
U.S. Pat. No. 3,448,648 describes an apparatus for trimming hollow articles which includes means for clamping the articles in a predetermined orientation and a cylindrical knife assembly which passes over the clamped articles to sever a flange or the like on the articles.
In order to resolve these disadvantages a choice has sometimes been made in favour of heating the blade so that the plastic material of the bottles melts as the cut is being made. This achieves reduced friction between the blade and the bottle, and the cut can be made faster. After the cut, however, and due to the melting of the material carried out by the blade, the bottles have a burr at the mouth that subsequently has to be removed, which involves increased costs and extra manufacturing time.